So ..... the whole reason for the post by you first off was to do nothing but whine and complain about a truck you bought used and are surprised that it had broken and stripped screws?
Wow.
Even then it shouldn't take hours to work on it. Using correct tools or even some tips learned from all your R/C experience.
Try this. Take a Dremel (an R/C god like you should own a Dremel) and cut a slot in all the bad screw heads. Now you have flat head screw heads that can be used to take them out. After you get them out then toss them and buy new ones.
But I'm guessing you knew that.